64 
MOLLUSCA. 
whose external base are pedicles which support the eyes. They in- 
habit the rivers of hot countries *. In the 
Calyptr/EA, Lam. 
Wc observe a conical shell in the hollow of which is a little lamina 
that projects inwards, resembling the commencement of a columella, 
and that interposes itself between a fold of the abdominal sac. The 
branchi* are comjjosed of a range of numerous filaments, long and 
slender, like hairs. 
In some of them this lamina adheres to the bottom of the cone, 
being itself bent into a portion of a cone or of a tube, and descending 
vertically!. 
In others it is almost horizontal, and adheres to the sides of the 
cone, which is marked above by a spiral line that establislies some 
relation between their shell and that of a Trochus!. 
SiPEiONARiA, Sotcerhy. 
The shell of the Siphonaria^, which have been recently separated 
from the Patellae, at the first glance seems very similar to a flattened 
Patella, with radiating sulci; but its margin projects rather more on 
the right side, and it is excavated beneath by a slight furrow, which 
terminates at this prominence of the margin, to which there is a 
corresponding lateral hole in the mantle, for the introduction of 
Avater into the branchial caA'ity })laccd on the l)ack, that is closed on 
every other j)oint. The respiratory organ consist of a fcAV small 
lamellae, arranged in one transverse line on the roof of that caAUty; 
the tentacula seem to be wanting, the head being merely furnished 
Avith a narroAV vcil§. 
There are some sjECcies, in Avhich even this slight appearance of 
the canal, in the shell, is effaced, resembling in toto that of a Patella, 
excejjtin its summit, AAdiich is behind Ij. In the 
SiGARETuSj Adans. 
I’lie shell is flattened, its a]terture ample and round, and the spire 
A^ery moderate, its Avliorls rapidly enlarging and seen Avithin, but 
concealed during the life of the animal in the thickness of a fungous 
shield, Avhich projects considerably beyond it, as Avell as the foot, 
and Avhich is the true mantle. Before this mantle are an cmargina- 
. * Patella nentdidea, List., 545 — 36, andNaturf., XIII, v, 1,2 ; — Pat. borhonica, 
Bor)' Saiiit-Yincent, Voy. I, xxxvii, 2 ; and for the animal, Quoy and Gaym., Yoy. 
de Freycin., pi. 71, f. 3 — 6. 
d" Patella equestris, L., List., 548 — 38; — Pat. sinensis, Ib., 39 ; Pat. trocliiformis, 
Martini, I, xiii, 135; — Pat. auricula, Cliemu., X, clxviii, 1 628 — 29; — Pat. plicatu, 
Nat. Forsch., XVIII, 11, 12; — Pat. striata, Ib., 13. 
X Patella contorta, Nat. Forsch., IX, iii, 34, VIII, 11 — 14 ; — Pat. depressa, lb., 
xviii, ii, 11. 
§ Patella sipho ; — Siplwnovia concinna, Sowerb., Gen. of Shelhs, No. XXI. ; 5. 
exigua. Id., lb. See Savigny, Descr. de PEg., Zool. Gasrer., pi. iii, f. 3, and Coq., 
pi. ), f. 1. Some years ago M. Gray proposed a genus Gadini.a, (Philos. Magaz., 
April 1824) which is precisely the same as Siphonari.a. 
II Siplionaria tristensis, Sowerb., loc. cit. 
